The British Hydrolastic Suspension System

In the early 60’s, BMC (British Motor Corporation) was determined to introduce a new and modern car that had a spacious interior, good road handling characteristics, was easy on gas and gave the occupants a smooth ride. The company was working on the ADO16 (Amalgamated Drawing Office Project 16). The automobile had finally achieved its position as a necessity in British daily life. Car ownership had risen to a new level and automobile manufacturing was at an all time high.

The result of the BMC ADO16 project saw the introduction of the Morris 1100 in March 1962; the Austin 1100, MG 1100, and the Vanden Plas Princess 1100 followed shortly thereafter. All of these cars featured a new suspension system which was the first on a British car. The system was the brainchild of the well known British rubber engineer, Dr. Alex Moulton. The suspension system was known as the hydrolastic suspension. It was of a simple design and working principle while being very compact.

When a front wheel hit a bump, it would move upwards, forcing fluid out of a front displacer unit along a pipe running back into a displacer unit at a rear wheel, pushing that wheel downwards. The rear of the car would then rise as the front wheel rode over the bump so that the whole car remained more or less level. Austin 1100 advertising, at the time, described the suspension as having no metal springs, no shock absorbers – therefore no maintenance. It was an “Austin breakthrough”.

The official fluid used in the system consisted of 49% alcohol, 49% distilled water, 1% triethanolamine phosphate and 1% sodium mercaptobenzoythazole. The fluid was sealed in the system at the factory during assembly and the only adjustment necessary would be tire pressures dictated by global climates where the car was sold. Home mechanics, who later worked on the fluid system, usually used only alcohol and glycol antifreeze in a 50/50 ratio.

There were many other cars that used Dr. Moulton’s suspension system. These cars included: mini variants (1964-1971), Austin America (1968-1971), plus Wolseley, and Riley models. The liquid suspension system even showed up at the Indianapolis 500. From 1964 to 1969 the “MG Liquid Suspension Special” ran in the prestigious race. The car was developed by the head of BMC in San Francisco, Kjell Qvale and race rngineer Joe Huffaker. In closing, I would like to thank BAC member J.J. Brown for his technical assistance and advice on this article. J. J. has an excellent working knowledge of the hydrolastic system as he owns two Vanden Plas Princess cars, a 67 MKI and a 72 MKIII as well as a 69 Austin America.


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